Macular degeneration has become one of the leading causes of blindness in adults. This disease affects the central retinal area known as the macula. The macula is responsible for acute vision—i.e., vision for such things as driving or reading a newspaper. Macular degeneration can lead to a gradual or sudden loss of vision to the level of 20/200 or less. Commonly, loss of vision only affects the central macular area of about 0.25 to 4 square millimeters, and does not usually progress beyond this area, thereby leaving 95–99% of the retina unaffected. Thus, reading and driving vision can be lost, while peripheral vision remains intact. This condition is often referred to as low vision.
Most cases of macular degeneration are untreatable, although laser photocoagulation has been successful in certain instances. Telescopic systems that attach to eye glasses also have been used for many years to improve vision in patients with macular degeneration. These systems, which work by increasing the retinal image of a given object, have not been very successful because they restrict the visual field to about 11° so that normal activity is not possible. They are also large and bulky. Attempts have been made to increase the visual field by putting part of the telescope within the eye. A Galilean telescope is useful for this purpose and consists of a converging objective lens and a diverging ocular lens, which together produce a telescopic effect.
U.S. Pat. Nos. 4,666,446 and 4,581,031, both to Koziol and Peyman, and both of which are incorporated by reference herein, each disclose intraocular lenses which are implanted in the eye in place of the natural lens to redirect the rays of light to minimize the adverse affect on vision caused by the macular degeneration of the eye. For example, U.S. Pat. No. 4,666,446 discloses an intraocular lens comprising a first portion including a diverging lens and a second portion including a converging lens. The converging lens provides the eye with substantially the same focusing ability of the natural lens prior to implantation of the intraocular lens. Thus, the eye will have decreased visual acuity due to the macular degeneration, but will also have unrestricted peripheral vision. The diverging lens, on the other hand, when combined with a converging lens positioned outside of the eye (e.g., a spectacle lens), provides a magnified image with increased visual acuity but a restricted visual field. Therefore, this type of intraocular lens creates a teledioptic lens system, which provides the patient with the choice of unmagnified but peripherally unrestricted vision or magnified but peripherally restricted vision.
U.S. Pat. No. 6,197,057 to Peyman and Koziol, the entire contents of which are herein incorporated by reference, relates to a lens system that combines a high plus lens with a plus and minus intraocular lens (IOL), so that the lens system works in a manner similar to a Galilean telescope. Generally the high plus lens is outside the eye (i.e., in glasses or spectacles or in a contact lens) and the plus and minus lens is an IOL that replaces or works in conjunction with the natural lens of the patient (See FIGS. 1 and 2).
U.S. Pat. Nos. 4,074,368 and 6,596,026 B1, the entire contents of which are herein incorporated by reference, both disclose telescopic implants for implantation within an eye. These implants are designed to replace the natural lens in the eye with a telescope. They are rigid devices requiring a large incision in the eye to implant.
Although all of these systems are beneficial to patients with macular degeneration, a continuing need exists for an intraocular implant that can correct for low vision in the eye.